1. Field of the Invention
The present invention relates to an inkjet printer to eject ultraviolet curable ink and a printing method for printing with ultraviolet curable ink.
2. Discussion of the Background
Generally, an inkjet printer of a type ejecting ultraviolet curable ink (UV ink) includes an inkjet head unit having an inkjet head for ejecting UV ink, and an ultraviolet light irradiation unit for emitting ultraviolet light to the UV ink ejected from the inkjet head and deposited on a medium. The UV ink is an ink of a media radical polymerizable type, a cation polymerization reaction type. The UV ink has a property that it is cured by polymerization when irradiated with ultraviolet light.
For curing UV ink, a large-size ultraviolet light irradiation unit is necessary. To solve this problem, JP-A-2004-188920 describes an inkjet printer provided with an ultraviolet light irradiation unit for emitting ultraviolet light to such an extent that UV ink is prevented from blurring. By irradiating the UV ink with ultraviolet light from the ultraviolet light irradiation unit a predetermined number of times, the UV ink is prevented from blurring. This structure attempts a reduction in size of the ultraviolet light irradiation unit. The contents of JP-A-2004-188920 are herein incorporated by reference in their entirety.
However, in the inkjet printer disclosed in JP-A-2004-188920, the ultraviolet light emitted from the ultraviolet light irradiation unit is low intensity and constant so that the ultraviolet light irradiation unit is required to emit ultraviolet light repeatedly. Therefore, there is a problem that it is impossible to effectively cure the UV ink.
Furthermore, there is an idea to provide an ultraviolet light irradiation unit for emitting ultraviolet light of such light intensity as to temporarily cure the UV ink and an ultraviolet light irradiation unit for emitting ultraviolet light of such light intensity as to finally cure the UV ink. Since two ultraviolet light irradiation units are necessary in the inkjet printer, however, there is a problem that the cost is increased.